T Follicular Helper Cells as a Therapeutic Target for Autoimmune Diseases

T follicular helper (Tfh) cells are specialized to provide help to B cells and to induce durable antibody response. Our knowledge on the biology of Tfh cells and their contribution to autoimmunity has significantly increased in the past decade. In particular, recent progress in understanding the relationship between blood CXCR5⁺ CD4⁺ memory T cells and the Tfh lineage cells in lymphoid organs has made the monitoring of ongoing Tfh responses in humans more feasible than before. Importantly, recent studies show that the dominant cytokines associated with the development of Tfh cells differ between mice and humans, indicating the importance of studies in humans. This chapter first summarizes current knowledge of the biology of Tfh cells with a particular focus on human Tfh cells and their association with the pathogenesis of autoimmune diseases. Then, it discusses potential strategies to target Tfh cells and/or molecules as a therapeutic modality of autoimmune diseases.